KR102181745B1 - Differential phase radar bio-signal detection apparatus and method - Google Patents

Abstract

The present invention relates to a differential phase Doppler radar bio-signal detection apparatus and method, and more particularly, in detecting a bio-signal, a differential capable of efficiently removing noise due to movement of a living organism and accurately measuring a necessary bio-signal It relates to a phase Doppler radar bio-signal detection apparatus and method. The differential phase Doppler radar bio-signal detection apparatus according to an embodiment of the present invention includes a transmission unit that transmits a signal to a living organism, a plurality of receiving units that receive signals reflected from the living organism, and a living organism using signals received by the plurality of receiving units. We present a configuration including a signal processing unit that removes components caused by the motion of and acquires a biosignal.

Description

Differential phase radar bio-signal detection device and method {DIFFERENTIAL PHASE RADAR BIO-SIGNAL DETECTION APPARATUS AND METHOD}

The present invention relates to a differential phase Doppler radar bio-signal detection apparatus and method, and more particularly, in detecting a bio-signal, a differential capable of efficiently removing noise due to movement of a living organism and accurately measuring a necessary bio-signal It relates to a phase Doppler radar bio-signal detection apparatus and method.

In recent years, interest in Doppler radar for detecting bio-signals is increasing rapidly. Doppler radar is a system that transmits a single frequency continuous wave to receive a phase modulated continuous wave reflected by a moving object. The phase signal modulated by the continuous wave includes displacement information on the motion of the object over time. The biosignal detector using such a Doppler effect may detect a heart rate, a respiratory cycle, and the like by receiving a signal that is phase modulated by a physiological movement caused by a person's heartbeat and breathing. The Doppler radar has the advantage of being able to measure biological signals from a distance without contact, and is not affected by the external environment and has a simple structure. Therefore, it can be applied to various fields such as monitoring the heart rate of a patient, home healthcare, and measuring the heart rate of a vehicle driver, and research for this is actively being conducted.

~180

로 제한되는 문제점을 해결하기 위해 extended differentiate and cross multiply (DACM) 알고리즘이 제안되었다.Since human bio-signals are very small movements, there is a null point problem that cannot be detected with one sine wave depending on the distance between the Doppler radar and the subject. To solve this problem, a Doppler radar structure that outputs I and Q signals having perpendicular phases has been proposed. The Doppler radar having such a receiver structure uses a complex signal demodulation method or arctangent demodulation method for I and Q baseband signals obtained from the receiver, regardless of the distance between the radar and the subject. Bio-signals can be detected. In addition, in the arctangent demodulation method, the conjugate of the arctangent function is -180

~180

The extended differentiate and cross multiply (DACM) algorithm was proposed to solve the problem limited to

Although many technical problems have been solved as research on Doppler radar for bio-signal detection progresses, when a bio-signal is actually detected using a Doppler radar, even a slight body movement (0.5cm~2cm) is larger than the bio-signal. There remains a serious problem of distorting the bio-signal as it becomes a noise signal. Therefore, accurate biological signals can be detected only by removing noise caused by arbitrary body movements, not movements caused by heartbeat and breathing. Accordingly, software and hardware-based methods for removing arbitrary body movements are being studied. However, the software-based method has the disadvantage that it can only remove movement of a predetermined pattern or it takes a long time to obtain an accurate result. In addition, the currently proposed hardware-based methods are difficult to implement because they use a radar of a complex structure or require an additional device such as a camera, and improvement is required in terms of cost.

Accordingly, an object of the present invention is to provide an apparatus and method for removing noise generated by arbitrary body movement and detecting a biosignal using a differential phase signal.

The differential phase radar bio-signal detection apparatus according to an embodiment of the present invention for solving the above problem includes a transmitting unit for transmitting a signal to a living organism, a plurality of receiving units for receiving signals reflected from the living organism, and the plurality of receiving units. It may include a signal processing unit that removes a component caused by the movement of a living body using the received signal and obtains a bio-signal.

According to an embodiment of the present invention, it may further include a signal converter for converting the signal received from the receiving unit into a digital signal and transmitting the converted signal to the signal processing unit.

According to an embodiment of the present invention, the receiver may be disposed in a symmetrical position with the transmitter at the center.

According to an exemplary embodiment of the present invention, the receiving unit may be included in four vertical, left, and right positions centered on the transmitting unit.

According to an embodiment of the present invention, the signal processing unit may obtain a differential phase of signals received by the plurality of receiving units to remove noise due to movement of a living organism and obtain a biosignal.

According to an embodiment of the present invention, the signal processing unit may obtain a differential phase by converting signals received from the plurality of receiving units into I/Q baseband signals and using them.

According to an embodiment of the present invention, the signal processing unit may obtain a differential phase after removing the dynamic DC offset of the baseband signal.

According to an embodiment of the present invention, an I/Q baseband signal having a differential phase as a declination angle may be obtained by using the baseband signal from which the dynamic DC offset is removed.

According to an embodiment of the present invention, the signal processing unit may obtain a differential phase by dividing the I/Q baseband signal having the differential phase as a declination angle by the size of an amplitude noise component and demodulating it.

In order to solve the above problem, a method for detecting a biometric signal from a differential phase radar according to an embodiment of the present invention includes the steps of: a transmitter transmitting a signal to an organism, and a plurality of receiving units receiving signals reflected from the living organism at a plurality of locations. And removing a component due to movement of a living organism using a plurality of signals received at the plurality of locations and obtaining a biosignal.

According to an embodiment of the present invention, in the signal reception step, the plurality of receivers may be arranged at a symmetrical position with the transmitter at the center.

According to an exemplary embodiment of the present invention, the receiving unit may be included in four vertical, left, and right positions centered on the transmitting unit.

According to an embodiment of the present invention, in the obtaining of the biosignal, the differential phase of the signals received by the plurality of receivers may be obtained to remove noise caused by movement of a living organism and obtain a biosignal.

According to an embodiment of the present invention, the step of obtaining the biosignal may include converting signals received from the plurality of receivers into I/Q baseband signals to obtain a differential phase.

According to an embodiment of the present invention, the step of obtaining the biosignal may further include obtaining a differential phase after removing the dynamic DC offset of the baseband signal.

According to an embodiment of the present invention, the step of obtaining the biosignal may further include calculating and obtaining an I/Q baseband signal having a differential phase as a declination angle using the baseband signal from which the dynamic DC offset is removed. .

According to an embodiment of the present invention, the step of obtaining the biosignal may further include obtaining a differential phase by dividing the I/Q baseband signal having the differential phase as a declination angle by the size of an amplitude noise component and demodulating it.

According to the present invention, it is possible to remove body movements of living organisms and accurately measure biometric signals.

In addition, it is possible to provide a technology capable of more accurately detecting a measured biological signal by removing the motion of a living organism and measuring a biological signal, and by catching signal modulation by noise additionally generated in addition to the motion than the existing technology.

In addition, it can be easily applied with a simple design change without the need to introduce a new device to an existing biosignal detection device and method.

1 is an example of a Doppler radar bio-signal detection apparatus.
2 is an example of a Doppler radar bio-signal detection apparatus for removing a movement of a living body.
3 is a block diagram of a Doppler radar bio-signal detection apparatus according to an embodiment of the present invention.
4 is a block diagram of a Doppler radar bio-signal detection apparatus according to an embodiment of the present invention.
5 is an example of a method for removing a dynamic DC offset of a baseband signal according to an embodiment of the present invention.
6 is an example of a method of obtaining a differential phase using a baseband signal according to an embodiment of the present invention.
7 is an example of an arrangement of a transmitting and receiving unit of a Doppler radar bio-signal detection apparatus according to an embodiment of the present invention.
8 is a flowchart of a method for detecting a biosignal of a Doppler radar according to an embodiment of the present invention.

Hereinafter, the'differential phase Doppler radar bio-signal detection apparatus and method' according to the present invention will be described in detail with reference to the accompanying drawings. The described embodiments are provided so that those skilled in the art can easily understand the technical idea of the present invention, and the present invention is not limited thereto. In addition, matters expressed in the accompanying drawings are schematic drawings for easy explanation of embodiments of the present invention and may be different from the actual implementation form.

Meanwhile, each component expressed below is only an example for implementing the present invention. Accordingly, in other implementations of the present invention, other components may be used without departing from the spirit and scope of the present invention.

In addition, each component may be implemented with purely hardware or software, but may be implemented with a combination of various hardware and software components that perform the same function. In addition, two or more components may be implemented together by one piece of hardware or software.

In addition, the expression'including' certain elements is an expression of'open type' and simply refers to the existence of the corresponding elements, and should not be understood as excluding additional elements.

1 is an example of a Doppler radar bio-signal detection apparatus.

Referring to FIG. 1, a conventional Doppler radar for detecting a bio-signal sends a signal generated by an oscillator to a living organism through a transmitting unit TX, and then a signal reflected from the living organism is received at the receiving unit RX. It can receive and detect a bio-signal. The conventional Doppler radar for detecting bio signals consists of one receiver and one transmitter, and uses a direct conversion structure to simplify the structure. In order to solve the null point problem, a structure is taken to demodulate the I/Q quadrature signal. A single frequency continuous wave is propagated by the radar transmitter and a phase modulated signal is received by the receiver to detect heartbeat and respiration signals.

However, in a conventional Doppler radar for detecting a bio-signal, when a living body is not stationary and accompanied by body movement, both the bio-signal and the body motion noise signal are included in the phase signal demodulated through the receiving unit. Accordingly, the demodulated phase signal can be expressed as a linear sum of the bio-signal and the body motion signal. In general, since the body motion signal has a larger signal size than the bio-signal, an accurate bio-signal cannot be detected. When such a structure is used to detect an actual bio-signal, there is a problem that a detection error is liable to occur because the subject is not stopped without any movement.

2 is an example of a Doppler radar bio-signal detection apparatus for removing a movement of a living body.

Referring to FIG. 2, a Doppler radar structure using two transmitters and a receiver has been proposed as a conventional Doppler bio-signal detection apparatus for removing a motion of a living body. This is a method of removing arbitrary body movements using phase signals measured by the transmitter and receiver by disposing two Doppler radar songs and receivers having the structure as shown in FIG. In order to demodulate the phase, a complex signal demodulation method is used, and arbitrary body movements are removed by multiplying signals detected from the front and rear. Such a demodulation method has a disadvantage in that there is a high possibility of a detection error with respect to a large motion because the DC offset included in the baseband signal and the change in AC amplitude are not considered. In addition, the radar arrangement in both directions as shown in FIG. 2 has a disadvantage in that it is difficult to apply to an actual application and the hardware configuration is very complex compared to the existing Doppler radar sensor.

3 and 4 are block diagrams of a Doppler radar bio-signal detection apparatus according to an embodiment of the present invention.

3 and 4, the Doppler radar bio-signal detection apparatus according to an embodiment of the present invention may include a transceiving unit 310, a signal processing unit 320, and a signal conversion unit 330.

The transmission/reception unit 310 may include a transmission unit 311 for transmitting a signal to the living organism 301 and a reception unit 312 for receiving a signal reflected from the living organism 301. The receiving unit 312 may be included in plural to individually receive signals at different locations. The signal received by the receiving unit 312 may include a biosignal. The bio-signals may include bio-signals such as heart rate, respiration, and pulse. Vibration caused by voice may be included in the biosignal.

The transmission unit 311 may transmit a single frequency continuous wave to the living organism 301. The transmission unit 311 may broadly include an electromagnetic wave, an electromagnetic wave, and the like, and may include an RF signal, an optical signal, and an ultrasonic wave, but is not limited thereto, and can transmit information. It can contain any kind of signal. The signal transmitted from the transmission unit 311 to the living body 301 may be reflected from the living body 301 and received by the receiving unit 312, and the reflected signal is related to the biosignal of the living body 301 May contain information. The signal may be reflected from the body of the living body 301 and phase-modulated by the bio-signal of the living body 301 to include information on the bio-signal.

The receiving unit 312 may receive a signal including information on the biosignal. The receiving unit 312 may be included in plurality. The plurality of receiving units 312 may be disposed at a plurality of locations, respectively, to receive signals. The receiving unit 312 may be arranged or located in a symmetrical shape with respect to the transmitting unit 311. The receiving unit 312 may be individually arranged or located in the upper, lower, left, and right sides around the transmitting unit 311. The receiving unit 312 may be arranged in a plurality in a circle centered on the transmission unit 311. After receiving the signal reflected from the living body 301, the receiving unit 312 may convert or drop the signal into a baseband signal. The receiving unit 312 may receive a signal reflected from the living body 301 and convert it into an I/Q baseband signal having a perpendicular phase therebetween.

만큼 위상 변조된 신호로, 여기서는 두 개의 수신부(312)를 사용하는 것으로 가정한다. 두 수신부(312)에서 출력된 I/Q 기저대역 신호는 수학식 4와 같이 표현 할 수 있다.The receiver 312 is the I/Q baseband signal

It is assumed that the signal is phase-modulated by the number, and two receivers 312 are used here. The I/Q baseband signals output from the two receivers 312 can be expressed as in Equation 4.

[Equation 4]

와

는 교류 신호의 진폭을 나타내며

와

는 기저대역 신호의 직류 오프셋 전압을 나타낸다. 여기서 직류 오프셋 전압은 피 측정자의 주변물체와 피 측정자의 위치 그리고 수신부(312) 회로 내에서 축적된 직류 오프셋이 모두 포함되어 나타난다. 위 식의 삼각함수에 포함된

는 송신하는 단일주파수 지속파의 파장,

는 송신 경로에 따른 residual phase offset을 의미한다.In the above equation

Wow

Represents the amplitude of the alternating signal

Wow

Denotes the DC offset voltage of the baseband signal. Here, the DC offset voltage appears to include all the surrounding objects of the subject, the location of the subject, and the DC offset accumulated in the circuit of the receiver 312. Included in the trigonometric function of the above equation

Is the wavelength of the transmitting single-frequency continuous wave,

Denotes a residual phase offset according to the transmission path.

The signal conversion unit 330 may convert a signal received by the reception unit 312 into an analog signal into a digital signal and a digital signal into an analog signal. The signal conversion unit 330 may provide the converted signal to the signal processing unit 320. The signal conversion unit 330 may convert the signal received by the receiving unit 312 into a signal in a form advantageous for processing by the signal processing unit 320.

The signal processing unit 320 may detect a biosignal by acquiring differential phases of signals received by the plurality of receiving units 312.

, 호흡신호

그리고 임의의 공통된 신체 움직임 신호

의 선형 합으로 나타낼 수 있다. 따라서, i 번째 수신부(312)에서 검출된 위상

는

로 나타낼 수 있다. 심장박동신호

와 호흡신호

는 주기적인 움직임 이므로 간단히 사인파의 형태로 나타낼 수 있으므로 첫번째 수신부(312)와 두번째 수신부(312)에서 검출되는 위상은 각각 수학식 1 및 수학식 2와 같이 근사적으로 표현 할 수 있다.According to an embodiment of the present invention, when the signal processing unit 320 detects a biosignal, the phase information included in the received signal is a heartbeat signal.

, Breathing signal

And any common body movement signal

It can be expressed as a linear sum of Therefore, the phase detected by the i-th receiving unit 312

Is

It can be expressed as Heartbeat signal

And breathing signals

Since is a periodic motion, it can be simply expressed in the form of a sine wave, so that the phases detected by the first receiving unit 312 and the second receiving unit 312 can be approximately expressed as in Equations 1 and 2, respectively.

[Equation 1]

[Equation 2]

과

은 진폭,

과

는 주파수, 그리고

와

는 각각 호흡과 심장박동에 대한 초기 위상을 의미한다. 또,

,

과

,

는 각각 두 수신부(312)에서 검출된 호흡과 심장박동에 의한 움직임의 진폭과 위상 차이를 말한다. 위의 두 식을 이용하여 차동위상

을 수학식 3과 같이 표현 할 수 있다.here,

and

Is the amplitude,

and

Is the frequency, and

Wow

Represents the initial phase for breathing and heartbeat, respectively. In addition,

,

and

,

Denotes the difference in amplitude and phase of movement due to respiration and heartbeat detected by the two receivers 312, respectively. Differential phase using the above two equations

Can be expressed as in Equation 3.

[Equation 3]

,

과

,

에 의해 결정된다. 따라서, 두 수신부(312)에서 검출된 생체 신호의 진폭과 위상 차이가 클수록 위상 차이 신호에서 더 큰 크기의 생체 신호로 나타난다. 반면, 두 수신부(312)에서 공통적으로 검출된 신호는 상쇄 되므로 이를 이용하면 공통된 신체 움직임을 상쇄하는 동시에 생체 신호를 검출 할 수 있게 된다.As can be seen from Equation 3, the differential phase signal includes frequency information of respiration and heartbeat. If the time domain signal is converted to a frequency domain signal, the magnitude of the frequency component of the biosignal is

,

and

,

Is determined by Accordingly, the larger the amplitude and phase difference of the biosignals detected by the two receiving units 312 are, the larger the biosignals appear in the phase difference signal. On the other hand, since the signals commonly detected by the two receivers 312 are canceled out, it is possible to cancel a common body movement and detect a bio-signal at the same time.

5 is an example of a method for removing a dynamic DC offset of a baseband signal according to an embodiment of the present invention.

만큼 위상 변조된 신호로, 본 발명의 일 실시 예에서는 두 개의 수신부(312)를 사용하는 것으로 가정한다. 두 수신부(312)에서 출력된 I/Q 기저대역 신호는 수학식 4와 같이 표현 할 수 있다.Referring to FIG. 5A, after the transmission signal is reflected on the body, the signal received by the receiving unit 312 is converted into an I/Q baseband signal. I/Q baseband signals are

It is assumed that the signal is phase-modulated by the number, and two receivers 312 are used in an embodiment of the present invention. The I/Q baseband signals output from the two receivers 312 can be expressed as in Equation 4.

[Equation 4]

와

는 교류 신호의 진폭을 나타내며

와

는 기저대역 신호의 직류 오프셋 전압을 나타낸다. 상기 직류 오프셋 전압은 피 측정자의 주변물체와 피 측정자의 위치 그리고 수신부(312) 회로 내에서 축적된 직류 오프셋이 모두 포함되어 나타날 수 있다. 위 식의 삼각함수에 포함된

는 송신하는 단일주파수 지속파의 파장,

는 송신 경로에 따른 잔류 위상 오프셋(residual phase offset)을 의미한다.here,

Wow

Represents the amplitude of the alternating signal

Wow

Denotes the DC offset voltage of the baseband signal. The DC offset voltage may appear by including all of the surrounding object of the subject, the location of the subject, and the DC offset accumulated in the circuit of the receiver 312. Included in the trigonometric function of the above equation

Is the wavelength of the transmitting single-frequency continuous wave,

Denotes a residual phase offset according to the transmission path.

와

그리고

와

는 일정한 값으로 근사할 수 있다. 하지만, 작은 움직임뿐 만 아니라 임의의 신체 움직임과 같은 큰 움직임이 포함된 경우

와

그리고

와

는 배경 산란(background scattering)의 변화와 움직임에 의한 피 측정자의 위치 변화로 인해 시간에 따라 변하는 변수가 된다. 따라서, 기저대역 신호에 포함된 위상정보를 정확히 검출하기 위해서는 시간에 따라 변하는 교류 신호의 진폭과 직류 오프셋에 대한 측정(calibration)이 필요하다. 본 발명의 일 실시 예에 따르면 기저대역 신호의 I, Q 신호간의 교류 신호 진폭에 대한 차이는 Gram-Schmidt procedure 또는 digital-IF 구조의 수신부(312)를 이용하여 측정(calibration) 할 수 있으며 여기서는 I, Q 신호간의 교류 신호 진폭에 대한 차이는 무시한다.The Doppler radar bio-signal detection device detects motion smaller than the wavelength of the transmitted signal.

Wow

And

Wow

Can be approximated to a constant value. However, not only small movements but also large movements such as arbitrary body movements are included.

Wow

And

Wow

Is a variable that changes over time due to the change in background scattering and the change in the position of the subject due to movement. Therefore, in order to accurately detect the phase information included in the baseband signal, it is necessary to measure the amplitude and DC offset of the AC signal that change over time (calibration). According to an embodiment of the present invention, the difference in the amplitude of the AC signal between the I and Q signals of the baseband signal can be measured using the Gram-Schmidt procedure or the digital-IF structure receiving unit 312, where I The difference in the amplitude of the AC signal between the and Q signals is ignored.

를 복조하기 전에 기저대역 신호에 포함된 직류 오프셋을 제거해 기저대역 신호를 만들 수 있다. 직류 오프셋은 기저대역 신호의 I/Q trajectory에서 원의 중심으로 생각할 수 있다. 상기 신호처리부(320)는 시간에 따라 변하는 직류 오프셋은 원의 중심을 동적으로 추적해 얻을 수 있다. 여기서는 단위 시간을 나누어 수신된 원들의 중심을 계산한다. 샘플링 된 기저대역 I/Q 신호들 전체를 (

[1],

[1]), (

[2],

[2])

(

[N],

[N]) 이라고 할 때, 적당한 단위 길이

으로 샘플링 데이터를 나누어 단위 시간 원으로 정의한다. 이때, 단위 시간 원의 직류 오프셋과 교류 진폭은 일정하다고 근사할 수 있다. 단위 시간 원의 중심은 수학식 5와 같은 최적화 함수를 계산하여 얻을 수 있다.Referring to Figure 5 (b), the signal processing unit 320 is a differential phase signal

A baseband signal can be created by removing the DC offset included in the baseband signal before demodulating. The DC offset can be thought of as the center of the circle in the I/Q trajectory of the baseband signal. The signal processing unit 320 may obtain a DC offset that changes with time by dynamically tracking the center of a circle. Here, the center of the received circles is calculated by dividing the unit time. All of the sampled baseband I/Q signals (

[1] ,

[One]), (

[2] ,

[2])

(

[N],

[N]), the appropriate unit length

Divide the sampling data by and define it as a unit time circle. At this time, it can be approximated that the DC offset and the AC amplitude of the unit time circle are constant. The center of the unit time circle can be obtained by calculating an optimization function as shown in Equation 5.

[Equation 5]

에 의해 결정된다. 상기 신호처리부(320)에서 기저대역 신호에서 직류 오프셋이 제거 되고 나면 도 5 (b)와 같이 원들의 중심이 I/Q 직교평면에서 원점에 위치하게 된다. 제안된 차동위상을 수신하는 도플러 레이다에서 위상 차이는 직류 오프셋이 정확히 제거 된 후 얻을 수 있으며 직류 오프셋이 남아있게 되면 차동위상 신호를 계산하는데 오류가 발생하게 될 수 있다.Here, the m-th DC offset value is

Is determined by After the DC offset is removed from the baseband signal in the signal processing unit 320, the centers of the circles are located at the origin in the I/Q orthogonal plane as shown in FIG. 5(b). In the Doppler radar receiving the proposed differential phase, the phase difference can be obtained after the DC offset is accurately removed, and if the DC offset remains, an error may occur in calculating the differential phase signal.

6 is an example of a method of obtaining a differential phase using a baseband signal according to an embodiment of the present invention.

Referring to FIG. 6, before the phase difference demodulation process, the signal processor 320 calculates a quadrature phase signal having a phase difference between two received signals as a declination angle. After calibrating the dynamic DC offset, the received I/Q baseband signal can be calculated by Equation 6 as shown in FIG. 6 (a).

[Equation 6]

는 위상 차이 복조과정에서 영향을 주지 않는 상수이므로 무시할 수 있다. 따라서, 도 6 (b)의 차동 위상 신호를 편각으로 갖는 직각위상 신호

는 위의 I/Q 기저대역 신호를 이용하여 수학식 7과 같이 계산될 수 있다.Where residual phase

Is a constant that does not affect the phase difference demodulation process and can be ignored. Therefore, the right angle phase signal having the differential phase signal of Fig. 6 (b) as a declination angle

Can be calculated as in Equation 7 using the I/Q baseband signal above.

[Equation 7]

.

.

는 여전히 교류 진폭

을 포함 하고 있지만, 이는 제안된 위상 차이 복조 과정에서 정확한 차동위상 정보를 얻기 위해 상쇄 될 수 있다.Equation 7 can be obtained using a simple trigonometric function. Right angle phase signal with differential phase as a declination angle

Is still alternating amplitude

Is included, but this can be canceled to obtain accurate differential phase information in the proposed phase difference demodulation process.

The signal processing unit 320 calculates a quadrature phase signal having a differential phase as a declination angle, and then performs a process of demodulating the differential phase. The signal processing unit 320 may demodulate a signal using a complex signal demodulation (CSD) method and an amplitude-compensated complex signal demodulation (ACCSD) method improving CSD. The ACCSD method can extract only accurate phase information by mitigating the influence of the AC amplitude of the baseband signal.

It can be demodulated by applying CSD to a right-angled phase signal having the differential phase as a declination angle using Equation 8.

[Equation 8]

.

.

는 잡음신호이다. 상기 CSD로 복조하면 복조된 신호에 차동위상이 아닌 잡음 신호

가 여전히 포함될 수 있다. 상기 복조된 신호를 FFT 처리 할 경우 그 결과는 위상차이 신호인

와 교류 진폭 잡음 요소인

의 convolution 형태로 나타나게 된다. 따라서 온전한 위상차이 정보를 얻기 위해서는 진폭 잡음 신호가 제거 되어야 하며 이는 ACCSD 방법으로,

로 나눈 수학식 9를 계산해 수행될 수 있다. here,

Is the noise signal. When demodulating with the CSD, the demodulated signal is a noise signal that is not in differential phase.

Can still be included. When the demodulated signal is subjected to FFT processing, the result is a phase difference signal.

And AC amplitude noise factor

Appears in the form of convolution of. Therefore, in order to obtain complete phase difference information, the amplitude noise signal must be removed. This is the ACCSD method,

It can be performed by calculating Equation 9 divided by.

[Equation 9]

The differential phase signal demodulated using the ACCSD method is free from AC amplitude noise caused by large body movements. As can be seen from Equation 9, the AC amplitude can be calculated and obtained from the baseband signal from which the DC offset has been removed.

7 is an example of an arrangement of a transmitting and receiving unit of a Doppler radar bio-signal detection apparatus according to an embodiment of the present invention.

Referring to FIG. 7, in the Doppler radar bio-signal detection apparatus according to an embodiment of the present invention, a plurality of receivers may be disposed around a transmitter 311.

라 하면, 6개의 차동위상 신호로 더욱 복잡한 형태의 신체 움직임을 상쇄할 수 있다. 생명체(301)가 앞-뒤, 위-아래, 그리고 좌-우로 움직이는 경우 6개의 차동위상 모두 움직임을 상쇄 할 수 있으며 상기 생명체(301)가 양 옆으로 비트는 움직임은

, 구부리는 움직임은

에 의해 상쇄 할 수 있다. 본 발명의 일 실시 예에 따른 도플러 레이더 생체신호 검출 장치 상기한 방법을 이용해 복잡한 신체 움직임을 제거할 수 있을 뿐만 아니라 높은 신호 대 잡음비를 갖는 검출이 가능하다. When a signal is received by the four receivers 312 as shown in FIG. 7, the four receivers 312 may detect a differential phase with each other receiver 312. 7 shows the differential phase between the receiving units 312

In other words, six differential phase signals can cancel out more complex body movements. When the living organism 301 moves forward-backward, up-down, and left-right, all six differential phases can cancel the movement, and the movement of the living organism 301 twists sideways

, The bending movement

Can be offset by Doppler radar bio-signal detection apparatus according to an embodiment of the present invention Using the above-described method, complex body movements can be eliminated and detection with a high signal-to-noise ratio is possible.

의 공통된 신호를 추출해 내기 위해 차동위상 신호끼리의 교차연관(cross-correlation)하는 방법을 사용한다. 즉, 연산자

를 교차연관(cross-correlation)이라고 하면 아래와 같은 수학식 10을 통해 차동위상 신호 간의 공통신호를 찾을 수 있다.Differential phase signal demodulated using differential phase demodulation method

In order to extract the common signal of the differential phase signal, a method of cross-correlation is used. That is, operator

If is referred to as cross-correlation, a common signal between differential phase signals can be found through Equation 10 below.

[Equation 10]

=

=

는 복수의 수신부(312)를 이용해 획득한 차동위상 신호이다. 상기 복수의 차동위상 신호를 전부를 사용하지 않고 그 중 몇 개만을 사용하여 신호처리 시간을 줄일 수 있으며, 교차연관(cross-correlation)을 수학식 11과 같이 주파수 도메인에서 진행할 경우 신호처리 시간을 단축 할 수 있다.here,

Is a differential phase signal obtained using the plurality of receivers 312. It is possible to reduce the signal processing time by not using all of the plurality of differential phase signals, but by using only a few of them, and when cross-correlation is performed in the frequency domain as shown in Equation 11, the signal processing time is shortened. can do.

[Equation 11]

=

=

After each of the differential phase signals is subjected to fast Fourier transform as shown in Equation 11, cross-correlation can be calculated by conjugate products thereof.

The Doppler radar bio-signal detection apparatus according to an embodiment of the present invention does not use all of the antennas of the receiving unit 312 with the same polarization in a differential phase Doppler radar including a plurality of receiving units 312 or including two receiving units 312. The system can be configured to have different polarizations. Since the size and phase of the received bio-signals vary according to the antenna polarization, the antenna of the receiving unit 312 that receives the heartbeat signal at the shortest distance is composed of a transmitter antenna and co-polarization, and the antenna of the other receiving unit 312 is If the antenna polarization of the wrong angle is used, the differential phase effect for the biosignal can be increased, and the effect of canceling the common body motion signal of a large size can be obtained.

8 is a flowchart of a method for detecting a biosignal of a Doppler radar according to an embodiment of the present invention.

Referring to FIG. 8, a method for detecting a Doppler radar bio-signal according to an embodiment of the present invention may include a step (S801) of transmitting a signal by a transmitter to an organism.

In step S801, a single-frequency continuous wave may be transmitted to the living organism 301. The signal transmitted by the transmitter 311 to the living organism 301 in step S801 may include an RF signal, an optical signal, and an ultrasonic wave, but is not limited thereto and may include all types of signals capable of transmitting information.

A method of detecting a Doppler radar bio-signal according to an embodiment of the present invention may include a step (S802) of receiving, by a plurality of receivers, signals reflected from the living organism at a plurality of locations.

In step S802, the signal transmitted from the transmission unit 311 to the living body 301 may be reflected from the living body 301 and received by the reception unit 312, and the reflected signal is the living body of the living body 301 It may contain information about the signal. The signal may be reflected from the body of the living body 301 and phase-modulated by the bio-signal of the living body 301 to include information on the bio-signal.

In step S802, the receiving unit 312 may receive a signal including information on the biosignal. The receiving unit 312 may be included in plurality. The plurality of receiving units 312 may be disposed at a plurality of locations, respectively, to receive signals. The receiving unit 312 may be arranged or located in a symmetrical shape with respect to the transmitting unit 311. The receiving unit 312 may be individually arranged or located in the upper, lower, left, and right sides around the transmitting unit 311. The receiving unit 312 may be arranged in a circular shape centered on the transmitting unit 311. After receiving the signal reflected from the living body 301, the receiver 312 may convert or drop the signal into a baseband signal. The receiving unit 312 may receive a signal reflected from the living organism 301 and convert it into an I/Q baseband signal having a perpendicular phase to each other.

만큼 위상 변조된 신호로, 여기서는 두 개의 수신부(312)를 사용하는 것으로 가정한다. 두 수신부(312)에서 출력된 I/Q 기저대역 신호는 수학식 4를 계산해 획득할 수 있다.In step S802, the receiving unit 312 is the I/Q baseband signal

It is assumed that the signal is phase-modulated by the number, and two receivers 312 are used here. The I/Q baseband signals output from the two receivers 312 may be obtained by calculating Equation 4.

만큼 위상 변조된 신호로, 본 발명의 일 실시 예에서는 두 개의 수신부(312)를 사용하는 것으로 가정한다. 두 수신부(312)에서 출력된 I/Q 기저대역 신호는 수학식 4를 계산해 얻을 수 있다.The signal received by the receiving unit 312 in step S802 is converted into an I/Q baseband signal. I/Q baseband signals are

It is assumed that the signal is phase-modulated by the number, and two receivers 312 are used in an embodiment of the present invention. The I/Q baseband signals output from the two receivers 312 can be obtained by calculating Equation 4.

The method for detecting a biosignal from a Doppler radar according to an embodiment of the present invention may include removing a component caused by a movement of a living body and obtaining a biosignal using a plurality of signals received at the plurality of locations (S803). .

In step S803, the signal processing unit 320 may detect a biosignal by acquiring a differential phase of signals received by the plurality of receiving units 312.

, 호흡신호

그리고 임의의 신체 움직임 신호

의 선형 합으로 나타낼 수 있다. 따라서, i 번째 수신부(312)에서 검출된 위상

는

로 나타낼 수 있다. 심장박동신호

와 호흡신호

는 주기적인 움직임 이므로 간단히 사인파의 형태로 나타낼 수 있으므로 첫번째 수신부(312)와 두번째 수신부(312)에서 검출되는 위상의 차동위상

을 상기 수학식 3을 계산해 획득할 수 있다.According to an embodiment of the present invention in step S803, the signal processing unit 320 includes the phase information included in the received signal when detecting a bio-signal is a heartbeat signal.

, Breathing signal

And random body movement signals

It can be expressed as a linear sum of Therefore, the phase detected by the i-th receiving unit 312

Is

It can be expressed as Heartbeat signal

And breathing signals

Since is a periodic motion, it can be simply expressed in the form of a sine wave, so the differential phase of the phase detected by the first receiver 312 and the second receiver 312

Can be obtained by calculating Equation 3 above.

In step S803, the difference in the amplitude of the AC signal between the I and Q signals of the baseband signal can be calibrated using the Gram-Schmidt procedure or the digital-IF structure receiver 312. Here, the AC signal between the I and Q signals The difference in signal amplitude is ignored.

를 복조하기 전에 기저대역 신호에 포함된 직류 오프셋을 제거해 기저대역 신호를 만들 수 있다. 직류 오프셋은 기저대역 신호의 I/Q trajectory에서 원의 중심으로 생각할 수 있다. 상기 신호처리부(320)는 시간에 따라 변하는 직류 오프셋은 원의 중심을 동적으로 추적해 얻을 수 있다. 여기서는 단위 시간을 나누어 수신된 원들의 중심을 계산한다. 샘플링 된 기저대역 I/Q 신호들 전체를 (

[1],

[1]), (

[2],

[2])

(

[N],

[N]) 이라고 할 때, 적당한 단위 길이

으로 샘플링 데이터를 나누어 단위 시간 원으로 정의한다. 이때, 단위 시간 원의 직류 오프셋과 교류 진폭은 일정하다고 근사할 수 있다. 단위 시간 원의 중심은 상기 수학식 5와 같은 최적화 함수를 계산하여 얻을 수 있다.In step S803, the signal processing unit 320 is a differential phase signal

A baseband signal can be created by removing the DC offset included in the baseband signal before demodulating. The DC offset can be thought of as the center of the circle in the I/Q trajectory of the baseband signal. The signal processing unit 320 may obtain a DC offset that changes with time by dynamically tracking the center of a circle. Here, the center of the received circles is calculated by dividing the unit time. All of the sampled baseband I/Q signals (

[1] ,

[One]), (

[2] ,

[2])

(

[N],

[N]), the appropriate unit length

Divide the sampling data by and define it as a unit time circle. At this time, it can be approximated that the DC offset and the AC amplitude of the unit time circle are constant. The center of the unit time circle can be obtained by calculating an optimization function such as Equation (5).

After the DC offset is removed from the baseband signal in the signal processing unit 320 in step S803, the centers of the circles are located at the origin in the I/Q orthogonal plane as shown in FIG. 5(b). In the Doppler radar receiving the proposed differential phase, the phase difference can be obtained after the DC offset is accurately removed, and if the DC offset remains, an error may occur in calculating the differential phase signal.

는 위의 I/Q 기저대역 신호를 이용하여 수학식 7을 계산해 얻을 수 있다.In step S803, before the phase difference demodulation process, the signal processing unit 320 calculates a quadrature phase signal having a phase difference between the two received signals as a declination angle. After calibrating the dynamic DC offset, the received I/Q baseband signal can be obtained by calculating Equation 6. A rectangular phase signal having the differential phase signal as a declination angle

Can be obtained by calculating Equation 7 using the above I/Q baseband signal.

는 여전히 교류 진폭

을 포함 하고 있지만, 이는 본 발명의 일 실시 예에 따른 위상 차이 복조 과정에서 정확한 차동위상 정보를 얻기 위해 상쇄 될 수 있다.In step S803, Equation 7 can be obtained using a simple trigonometric function. Right angle phase signal with differential phase as a declination angle

Is still alternating amplitude

However, this may be canceled to obtain accurate differential phase information in the phase difference demodulation process according to an embodiment of the present invention.

In step S803, the signal processing unit 320 calculates a quadrature phase signal having a differential phase as a declination angle, and then performs a process of demodulating the differential phase. The signal processing unit 320 may demodulate a signal using a complex signal demodulation (CSD) method and an amplitude-compensated complex signal demodulation (ACCSD) method improving CSD. The ACCSD method can extract only accurate phase information by mitigating the influence of the AC amplitude of the baseband signal.

In step S803, CSD may be applied to the quadrature phase signal having the differential phase as a declination angle using Equation 8 to demodulate it.

로 나눈 상기 수학식 9를 계산해 수행될 수 있다. In order to obtain complete phase difference information in step S803, the amplitude noise signal must be removed. This is the ACCSD method.

It can be performed by calculating Equation 9 divided by.

The differential phase signal demodulated using the ACCSD method is free from AC amplitude noise caused by large body movements. As can be seen from Equation 9, the AC amplitude can be calculated and obtained from the baseband signal from which the DC offset has been removed.

In the Doppler radar bio-signal detection method according to an embodiment of the present invention, the signal conversion unit 330 converts a signal received from the receiving unit 312 into an analog signal into a digital signal and a digital signal into an analog signal ( (Not shown) may be included. The signal conversion unit 330 may provide the converted signal to the signal processing unit 320. The signal conversion unit 330 may convert the signal received by the receiving unit 312 into a signal in a form advantageous for processing by the signal processing unit 320.

So far, the present invention has been looked at around its preferred embodiments. Those of ordinary skill in the technical field to which the present invention pertains will be able to understand that the present invention may be implemented in a modified form without departing from the essential characteristics of the present invention. Therefore, the disclosed embodiments should be considered from an illustrative point of view rather than a limiting point of view. The scope of the present invention is shown in the claims rather than the above description, and all differences within the scope equivalent thereto should be construed as being included in the present invention.

Claims (17)

A single transmission unit that transmits a signal to an organism;
A plurality of receivers for receiving signals reflected from the living organism; And
Including; a signal processing unit for removing a component due to the movement of the living organism from the plurality of signals received by the plurality of receiving units and obtaining a biosignal; and
By detecting the phase of each of the plurality of signals received from the plurality of signals and calculating the phase difference between the two signals, removing noise caused by the movement of living organisms and obtaining a biosignal,
The signal processing unit,
Converting the signals received by the plurality of receivers into I/Q baseband signals, removing the dynamic DC offset of the baseband signals, and obtaining a differential phase,
A differential phase radar bio-signal detection apparatus for calculating an I/Q baseband signal having a differential phase as a declination angle using the baseband signal from which the dynamic DC offset is removed. The method of claim 1,
A differential phase radar bio-signal detection apparatus further comprising a signal conversion unit for converting the signal received from the receiving unit into a digital signal and transmitting the converted signal to the signal processing unit.
The method of claim 1,
The plurality of receiving units,
A differential phase radar bio-signal detection device disposed at a symmetrical position with the transmitter at the center.
The method of claim 3,
The receiving unit,
Differential phase radar bio-signal detection apparatus including four at the top, bottom, left, and right positions around the transmitter.
delete delete delete delete The method of claim 1,
The signal processing unit,
A differential phase radar biosignal detection apparatus for obtaining a differential phase by dividing and demodulating the I/Q baseband signal having the differential phase as a declination angle by the magnitude of an amplitude noise component.
Transmitting a signal to a living organism by a single transmission unit;
Receiving a plurality of signals reflected from the living organism at a plurality of locations by a plurality of receivers; And
Including; removing a component caused by the movement of the living organism using a plurality of signals received at the plurality of locations and obtaining a biosignal; Including,
By detecting a phase of each of the plurality of signals received from the plurality of signals and calculating a phase difference between the two signals, removing noise caused by the movement of a living organism and obtaining a biosignal,
The step of obtaining the biosignal may include:
Converting the signals received by the plurality of receivers into I/Q baseband signals, removing the dynamic DC offset of the baseband signals, and obtaining a differential phase; And
Computing an I/Q baseband signal having a differential phase as a declination angle using the baseband signal from which the dynamic DC offset has been removed; a differential phase radar biosignal detection method further comprising.
The method of claim 10,
Receiving the plurality of signals at a plurality of locations,
Differential phase radar bio-signal detection method in which the plurality of receiving units are disposed at a symmetrical position with the transmitting unit at the center.
The method of claim 11,
The receiving unit,
Differential phase radar bio-signal detection method including four at the top, bottom, left, and right positions around the transmitter.
delete delete delete delete The method of claim 10,
The biosignal acquisition step,
Dividing the I/Q baseband signal having the differential phase as a declination angle by the magnitude of an amplitude noise factor and obtaining a differential phase for demodulating; differential phase radar biosignal detection method further comprising.

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